Sound recorder and reproducer



Feb. i4, 1950 J. OD. SHEPHERD SOUND RECORDER AND REPRODUCER I Filed Dec. 18, 1941 WL.. v

Pou/12 CoM/ERT.

INVENTOR age capacity is required for a given recording in- Y terval and the filament will be more expensive than if a round one is used. The reproduction arrangementsvto be described will effectively reproduce the record 'irrespectiveofthe orientation of the filament as lpresented to the reproducer.

A further feature of this invention is that it will permit a much longer recording period on asingle filament than is feasiblewitha disc or a cylinder record. This is particularly advantageous in the recording of a court yor the like proceeding, or the recording ofradio programs or other applications where continuous recording over a long period of time is necessary, inasmuch as a single large spool dit@ the like of filament can `be provided which will serve for many hours. This alsoY is true of dictation machines in that a large roll vof filament may be provided and the recorded portion removed fromztimeto time as desired for transcription. l Still a further feature is agrecorder which may be employed on vehicles or the like, such as aeroplanes. Relatively violent movement ofthe vearound driving roll I3 which has a suitable surface to drive the filament by friction. The lilament then passes over roller I4 similar to roller 8, and provided for the same general purpose, through the eyelet I5 of a level winder to the takeup spool or bobbin I6, which may be similar to spool 2.

Shaft 6 and spool 2 may be driven by motor |I and spool I6 with its associated shaft and gearing maybe driven by .motor I8.'v It is the purpose of these two motors to effect takeup, toy maintain the filament in tension and to drive the spools at comparatively high speed during rewinding or locating a particular portion of the record. Roll I3 is driven through clutch 20 by motor I9. It is to be understood that any suitable type of motors II, I8 and |9 m'ay be used to meet the general operating requirements as set out below, and

. speed reducing gearing may be employed between hicle will not affect the recording operation. The

use of disc or cylinder record type machines is difficult under such conditions. e

These and other-features of `this invention will be understood-from the drawing and description thereof which follow.

' With reference to the drawings,

Figure 1 shows a diagrammatical relation of `certain of the elements, with the framework and many of the parts whichmaybe of conventional: y.type omitted for clarity, of a-combined recorder fand reproducer.4 Figure 2` is .a partial section along the line II-II of Figure 1 showing the relation of the recording element and the filament.

Figure 3 shows sections of a record on a round filament in two differentl orientations, 90"y apart.

Figure 4 is an alternative arrangement for 4translating thel record into a modulated light beam.

Figure 5 is a circuit which may beused in practicing this invention. v. .v Y

Figure 6 shows a manually operable knob and index for controlling the operation of the invention. Y

With reference to Figure l, a filament I, which for the purpose of describing` the preferred em.- bodiment of this invention will be assumed and is shown to Ybe substantially round, is supplied from a bobbin or spool 2. Thisfilament passes through o an eyelet 3 attached tothe `distributing member of a conventional level winder, which is driven by gear- 4 meshed with gear. 5 attached to shaft 6 upon which spool 2 is removably attached. Clip 1 locksthe spool in position. It is to be understood that full spools of filament may be inserted on shaft or spindle 6 when` necessary to supply the device. Y

Filament I passes around roller` 8 rotatably mounted on rectangular shaft 9 slidably mounted in fixed bracket 9a. A 'spring I0 tends to maintain the roller to the right, being limited by collar II. It is the purpose of this arrangement to provide ayieldable element'as a protection to the filament against `shock arising from starting.

The filament then passesbver the plate I2. After said motors and their respective driven elements. Motor I9 preferably should .be of constant speed, so it may-be of the synchronous type Yor equipped with conventional governing means, not shown.

The plates of clutch 20 are normally maintained engaged by spring 2|. A clutch magnet 22, upon V being energized, attracts its armature 23 `and an extension thereof separates the plates vof the clutch to operatively disconnect motor I9 from roll I3.v

A pinion 24, attached to thedrive shaft'of the roller I3, is meshed with. gear 25 which drives a conventional counter 26, said counter being provided with resetting means indicated as a wing member 2'I. The gearing and counter are provided to indicate measurement of the. record. It is suitably calibrated in inches, centimeters, minutes or other appropriate units.

The recording device 30 basically may be similar to a familiar recording element used in the electrical recording of discphonograph and the like records. Such an element includes'a driving coil energized in response to sound or the like currents to drive a needle or stylus. In application to the instant purposes a suitabledesigned deformL ing blade 3| is employed instead of a needle or stylus. The device 3B is mounted so that the blade 3| will be driven transverse to the direction of movement of the filament. This is better shown by Figure 2 which is a partial section along the line lI-II of Figure l. The filament moves in a shallow groove in plate `|2` which may be as deep as approximately one-half the diameter'of the filament. During recording the blade 3| will b e driven in the vertical plane in response to voiceor similar currents to result in the filament being deformed or cut in accordance therewith to leave a corresponding record on the filament. The blade 3| may be wider than the groove as prog tection against the complete severance of the filament due to a sudden sounder other strong impulse received by the recording device.

It is contemplated that the'y blade 3|l may be biased electrically or mechanically as by a spring or rubber mounting so that itwill evenly distort or cut the filament in the Vabsence of incoming signals. The presence of signals will then cause the vibration of the blade above and below this normal position. This maybe provided to improve the quality of the record by preventing during recording the member 3| lifting clear of the filament for normal signal volumes.

The deforming or cutting arrangement as shown particularly by Figure 2 may be modified by providing a fixed blade similar to moving blade 3| underneath the filament'and in opposition to 5 blade 3| to result in undulati'ons being cut on' both the top and bottomof the fila-ment as seen in this fig-ure.` It also' is apparent that the blade 3f maybe driven by a diaphragm actuated in re sp'onse to sound wavesrather than by an electrical arrangement asv contemplated in the preferred embodiment of th-is invention.

' Figure 3 indicates a normally round filament with a record thereon, 32 indicating the' pron-lei left by the blade 3l', while' 33 indicates the' fila;A ment with a record turned through 901 from the presentation ofr 32.

Ar roller 42- with predetermined serrati'onson periphery may bei suitably' mounted in brackety 43- and normally maintained out ofengagementf with the filament by' virtue of spring, 45. .By manually; pressing button 44* the roller will engage the" fila-iV merit and deformit in accorda-nce Witli-the serra tions on the roller. This deformation will, on playback, result ini a particular tone or sound.4 'I-liismay be usedto override' a portion oi the recor'd or to' designate to a transeriber the end of a sentence, paragraph or other iniormation.l ThisI vroller may, of course, be operated magnetically' under control of aswitch in an energizing circuit.

.Y YIIZn order to reproducefrom the record, it may be revvound to spool 2 and again driven in the sameV direction and at the same speed as during the recording operation. A projector 34 pro; jects a beam of substantially parallel rays off lig-ht .or energy in the portion of' thev spectrum within or near thevisiblebandl, preferably mono#- ohromatic lig-ht, through a polarizing niediun'i 35, such as Polaroid which polarizes-the beaml in a particular direction. The beam then passes" through a slit in screen 36, said` slit beinginl the general orderof 1 mil. wide, although other widths maybe used. This presents a narrow ribbon of light through. which the-filament passes. A- slot 32T is provided in plate l2' for the beam.4 It then passes through polarizingV medium. {8f` which isy so oriented withy respect tomedium 35ras normally to substantially extinguish the beam; By vire tue of thev optically active property: ofv the lament, there will be a spot of liglhtabout as wider as the slit in screen 36.v and approximately as.y long as the diameter of the i'llax'rlent,f giving cons sideration. to the deforma-tion thereof' by the record, presentedtothe photo-'cell 40; This. conY templates a proper orientation of the polarizat-y tion of' they beam and rnediunir 38. with respect to theA filament; inview of.. the materiali and ine! ternal structure there,of,.to produce thiseifeot.`

It;will'be,recognized-,that by. adjustment ofthe polarizing medium 35 and? 38,Withz respect to each. other and the lament, atlightgbackgroundlmay be; producedinwhich the filamentwithout a rec--4 ord will form a shadow. A-.recordonthe lament` with this arrangement, will resultA in. the light which passes through thefilament. being; rota tivelyv modulated to result ina portion. of: it-'passl-y ingbeyond, the lower polarizing medium toire-- sult in` light intensity modulations detectable, by the photo-cell. The mediumsmayiofy course,.be. adjusted in praoticeto give either; allightzor; darle. background, or one between.

These arrangements will result, in., the; modu-zv lation by the recordpn, the iilament of the light which reaches the photo-cell.A Inf order, to f provethe modulation of the bear-na second screen` Bqwith a slit therein parallel to the-slitpinscreen 36 may be providedso that.when:the.lam'entis;` presented to the beam; assliowir. by 331',the-r eav fraction-arising from. the undillatonsa vmaybe tially constant volume will. bey reproduced irre.i

spective of the angle of presentation of the lament to the beam. In. order to improve this op@ eration, I may provide a curved prism or lens be# tween the opening 31 and screen 39 so that thev refraction effect when the filament is presented.

1l? of.; cams .familiarly known: tothe telephonev diff? as at 33 is. amplified, i. e., the angular swing of the'. beam is. increased by virtue. ofs'the prism or the: like. This may reduire', of course, that the screen 39 and the photo-cell 40 be located at a. proper angle off. the center line of the beam as projectedv by v34.

Another arrangement which may' be employed with respect to the reproduction portion'.- ot the device is shown by Figure'- 4'. This provides' for' two beams of light to pass through.- the.` nlamentatA approximately 96 with respect to each otheras a further means of compensation for variousv orientations of the filament. The beam of light from projector 34 strikes mirror 5| which die: vides it into two beams, said beams striking miti-i rors 52 and 53 which direct them through. lament I at. abouty 9109 with respect to` each. other;

. Screen 54 has two slits which reduces the Widtlr of each beam. to, say, 1 mil; Mirrors 55l and 56 intercept the beams, directing them through slits in screen- 5.1 to condensing lens 581` which projects them to photo-cell '40; ThisA arrange-f` ment may, of course', be used with'pola-rizing: means above and below the filament as' described?- in connection with Figure 1,. and the screen 5ft maybe omittedi Prisms or lenses may be enrpl'oyed instead of mirrors! to. provide' scanning: of the filament. through afwide. angle and tofdi rect themodulated raysv into ar p'hotoeeell".`

- A circuitwhich' may. be used with this nevica is'shown by Figure 5. .Circuitconventionszhave. been; employed` to indicate various of the. ele@ ments, A manually operable. control switchvv is provided tovconltrol the various fundamental op erations-of the device, one form of which is'. shown by Figure 6. In the latter gurea mans ually operableA rotatableknob 60 is suitably mounted on the cover of the' device and ispro'-I vided to opera-te contact closing means forvv ofi-1 fecting appropriate circuit operations.` Deside-L nations are provided' aroundl an arc with this knob as a centerand the pointer Gli indicatesthe.4 operations controlled' byl the various positions; oil.

the switch. Position 1i' is for' oft; position 2 is.;

on; .position-3, designated.Talk,. is for; recorder ing position' 4, designated Listen 'iso for producing; position 5,- designated. Fast,'is fon Idriving the filament in the-samedirection.asduifa4 n indicatedasaswitch2 62 of Figure 5, whiclnriiay` be on alcord or attaclled'tothemounting` ofthetransm'itter-receiver to be described.

The switching. mechanism controlled: .by knob.I 60. been. shownd conventionally.- as.' a plurality;l

as. Sequence switchv cams, Awith cptlng brushes. These cams are cut for six operative positions corresponding to the positionsv of the knob. A designation 5, for example, beside a brush indicates, as is conventional with diagrammatical representation of such cams, that a circuit is completed through the brush and cam in position 5. The designation 2/6 indicates closure for all position from 2 through 6, inclusive. An open triangle indicates a brush closure for fall,L positions.. Other contact closing arrange- :ments obviously may be employed.

fAnamplifler 63 is provided. This may be of conventional type to provide the gain necessary for the operation vof the device. It may include a plurality of electronic tubes. It is employed for both the recording and reproducing operations,lthe gains of which may be different. It is, therefore, to be understood that the transmitter-receiver, the recorder and the photo-cell may be appropriately connected and properly provided with circuit elements in the amplifier for the gains necessary for the .desired operation of each under 'the several operating conditions' of the device. The knob 60 may be employed to effect circuit control in the amplifier element for thevarious operations. The general level of amplifier may be controlled by gain control 64, of which more than one may be provided as desired. Conventional automatic volume control arrangements may also be incorporated in the design of the amplifier.

A suitable source of power is connected to terminals 65 and 66 which, it is assumed herein, will be of. the alternating current type of a conventional power frequency. lit will be apparent, however, that the device may be modiied to lbe powered from direct current. Cam A controls the power supply to the device. When knob 68 is turned to any of positions 2 through 6 this cam completes an obvious circuit to supply power to the amplier. Lamp 61 is appropriately connected to a D. C. supply in amplifier 63, or other suitable power supply. This,

lamp provides ythe scanning beam and it burning will indicate that the device is substantially ready for operation. Provisions may be made for its observance through a hole in projector 34. It is apparent that a separate lamp can be provided appropriately connected to indicate that the cathodes of the tubes of the amplier are heated to substantially their operating temperature.

In position 2 a circuit can be traced from terminal.65, the armature and upper back contact of relay l0, resistance 67, winding of motor I8 through the brushes and cam A to terminal 66. A similar circuit can be traced from terminal 65 through the lower back contact of the relay, resistance 68, winding of motor AII to terminal 66 via cam A. Under this condition sufiicient power is supplied motors Il and I8 to place filament .I under light tension. The use of resistances in series with these motors to reduce the power thereof is merely a conventional indication of the desired operation and may be modified as appropriate in light of the particular type or types of motors enipoyed in the practice of this invention. y

As a preliminary step toward making a record,

the knob 60 is turned to position 3. In this position a circuit can be traced from the transmitter-receiver 69 through cams D andE to the input of the amplifier. It is contemplated that thev transmitter-receiver kwill bea device V-art.

whichmay .be used to convert sound waves into undulating or alternating current, or to take such currents and convert themv intoY .sound waves, of which many forms are known to the Separate transmitters and receivers obviously may be employed with appropriate minor modification of the circuit arrangements, asy will be understood. Where a separate transmitter,

connected to a radio set, a telephone circuit or other source of signals to be recorded. The output'as represented by the -circuits to the right hand brushes of cams D and E may, of course, be extended to a loud speaker, a telephone circuit, a radio transmitter or other suitable device.

In position 3, theA recorder 30 is connected to the -output of the amplifier through cams Fand G. Sound picked up by element 69 will be amplified to ,result Ain corresponding energizationlof the recorder and the actuation of blade 3|.

When it is desired to start recording, switch 62 is closed which completes an obvious circuit for the operation of relay l0. Closure of the upper front contact of this relay will complete a circuit to energize self-starting drive motor gI9 to drive drum I3 and advance the filament at uniform speed past the recorder. By talking into the transmitter-receiver 69, a record will be made.

thereof on the filament. The switch 62 may be released to stop the recording as, for example.

during a pause indictating, and itag'ain may bejstarted by reoperation rof this switch.l Motors.

I1 and I8 are energized in position 3 by suflicient energy to maintain the filament in tension. Under the condition of recording, motor I8 will revolve to take up the slack in the record as it is paid outfrom roll I3 and motor I1 will be rotated by the filament in the direction opposite-v to that in Which it is tended to be rotated by its powerl supply. It will be noted that when relay 'l0 is operated, the reduced power supply tov motors I1 and I8 is furnished through the right hand brushes of cam B.

. At any time it is desired to play back the record, knob 60 is turned to position 6. v'Under this condition the circuit to motor I8 to maintain.

tension is partially opened at the upper right hand brush of cam B but the circuit through this brush is paralleled through the upper back contactand armature of relay 10. Operation of switch 62 will operate relay 'l0 as described above. This will cause full power to be delivered to motor I1 by a circuit from terminal 65, the lower armature and front contact of relay 10, cam C, the upper left and lower right hand brushes thereof,

winding of motor I1 to terminal 66 via cam A.'

The tension circuit for motor I8 will be opened at the back contact of the upper armature of the relay. The clutch magnet 22 will receive an obvious operating circuit in position 6-via cam B, thereby disconnecting motor I9 from drum I3 to reduce the load on the filament. Under this condition the record will be rewound as far as desired, the indication of counter 26 being observable to facilitate this. When it is desired to stop this rewinding process, switch 62 may be released to release relay 'I0 which will restore power through the -resistances of both motors I'l and I8 to provide lament tension.

Playback may be effected by turning knob 60 to position 4 which will connect photo-cell 40 to the input of the amplifier via cams H and I, and lwill connect transmitter-receiver 69 to the output of the ampliiier via the upper` right hand brushes of cams. D and E. Operation of switch 62 will energize motor I9 as described for recording to advance the record and effect reproduction therefrom.

. It may be that only a portion of the record is to be played back and it is desired again to record where the previous record was discontinued. Knob 60 may be moved to position 5, which will partially open the tension circuit for motor I'I at the lower right hand brush of cam B and will energize the clutch magnet by a previously described circuit through cam B. When switch 62 is operated, the resulting operation of relay 'I0 will furnish full driving current to motor I8 from power terminal 65 the lower armature and front contact of the relay, the upper brushes of cam C, the winding of motor I8 to power terminal 66 via cam A. The tension circuit for motor I'I will be opened at the lower back contact of relay le. Under these conditions the record will be wound rapidly on spool I 6. This winding operation may be discontinued by release of switch 62 when the counter'has indicated a fresh portion of the iilament is available. Knob 60 may then be moved to position 3 and the recording operation continued.

When the record is completed and it is desired to play it back in its entirety as, for example,

when a stenographer is to type a dictated record, it may be rewound as described above and then played back, observation of the counter enabling the rewinding operation to be stopped before the filament is completely unwound from spool I6.

Means may be provided to lift the blade 3| from the lament for all operating positions of 'Knob 60 except for recording position '3. This may be effected for such positions by connecting the recorder to a direct current supply, shown conventionally asV battery Il although Ai1; may,lof course, be a source of D. C. in the amplifier and power converter 63, which will be of such polarity and potential as to drive the blade 3l up clear of the filament. Thecircuit for this in'` positions ,2, 4, 5 and 6 may be traced from the lower terminal of battery 1I, the upper left hand and lower right hand brushes of cam F,l the Winding of recorder 30, the lower right hand and upper left hand brushes of cam G to the upper terminal of battery 1 I.

If a-at tape or ribbon is employed the'record may be made on the edge thereof, in which case it will have an edge presented to the blade 3! as viewed in Figure 2, for recording. The record then will be similar to 32 of Figure 3 except, of course, the ribbon or lm may be as wide as appropriate. It may be presented flat to the light beam for reproduction.

If a film is employed, the record may be made in the center of, or other appropriate path on, it by a cutting blade which may be formed as a chisel having a substantially V-shaped distorting or cutting edge similar to that disclosed in the Vermeulen et al. Patent No. 2,154,589 issued April 18, 1939, and the resulting record may be generally similar to that of Figure 2 of that patent, except that a homogeneous viilm of optically active material will be employed. The polarization of the light beam used in reproduction and the medium 38 of my Figure lmay be such as to extinguish the beam with a blank lilm.

The record which is cut in the `film will result in the rotationof the light rays so that the record with its undulations will be lvisible to the photocellas it is passed through` the light beam. The screen 39 may be omitted. ,The use of flat tapes or films will require appropriately shaped reels or thelike for supply and take up as will be underf stood. l

It is contemplated that in practicing this invention wide departure may befmade within its scope Iwith reference `to the storage means :for the lament, conventionally shown in the drawings as Vboblcins f2 and I6.` kWhere a long record as,for example, Jfor court proceedings or continuous recording of radio programs is required. each of the bobbins maybe yof sufficient size to contain the entire record.` The supply filament, as an alternative,y may be furnished wound .in the form of a rustrum of large capacity in the same general Way that :yarn is conventionally supplied Ito the knitting and weaving industry, whereby the filament will be delivered vfrom the tcp ol the cone without tanglingj. In-the `ern-- ployinent of such an arrangement a second wheel similarto I3 may be provided on the input side of the recorclel` equipped withv an appropriate drag, Aor other suitable means may be employed, to maintain the filament under. suitable tension.

The .takeup bobbin I6 may jbe .so constructed that one end ofv it andthe ,core may be removed after recording so that fthefllament may be supplied for playbackfrom. theinside, thereby obviating. the necessity Vofrewinding prior thereto. Inorder to facilitate delivery of the filament with such an arrangement, bobbin I 6 may be conically shaped. The bobbins may, offcourse, be. madeof an inexpensive material, such as cardboard.

I may provide anl arrangement for facilitating the location ,o i .a. particular portion of the vrecord by cooperating alinodied. counter such as AI5 with manually adjustable dials. `The patent of Messiter No. 1,307,369, datedJune24, 1919, shows such .an arrangement. TheY counter dials `may be provided with,V electricalY contacts and the manually adjustable vvdials Amay be similarly equipped in accordance `with the teachings ofv this patent. AA yrelay may be substituted for the bell |94 thereof, saidrelax7 .in operating stopping the winding operation by, 'for example, causing therelease .ofrelay 'Ill when the desiredcountis reached. By this arrangement themanuallyy ad. justable dials may` beset for the V countof the desired portion of the record and the winding operation started.. When this, count is reached the lila-ment will be stopped.`

f The arrangement-shown by Figure 1 is for both recording andreproducing. These two functions may be provided, of course, by separate machines by provision in each only those elements necessary for its particular operations.

Three motors are shown in Figure 1 to, provide the several operationsof thedevice. This has been done as an expedientA in setting out this invention. Itis lcontemplated that la, single motor, or two motors,y may be used with appropriate controls, gearing. and .other necessary mechanical elementsy toprovide the driving operations as `will be understood. e

While a lamcnt, tape or the like is particularly well adapted tothe purposes of this invention, it will be recognized that `it, can be adapted to employv a disc or cylinder' lrecord of optically active material which can be vcut in accordance with the received signals. Rep'roduc'fion,with such an arrangement' can'be 'effected bypassing a beam of polarized lightjthrough the record as Voriginally exposed nlm. The sound record may be directly made on the soundpath of the film by mechanical action in response` to the received sound as the picture is taken.

I may employ in claiming this invention terms such as optically active or having light rotative characteristic with respect to the material employed for the record medium. These may be considered as expressions relating to observable phenomena of certain light transmitting substances including materials, particularly of the cellulose group, having predetermined oriented grained structure, to in effect rotate polarized light and thereby make visible, by their introduction into a polariscope, a beam of normally extinguished polarized light, or the converse. Terms such as "light rotative modulations and others to this end may be considered as relating to the effect on a polarized scanning beam of a recordV such as described herein being passed through it. Furthermore. expressions in the claims relating to modulation of the scanning beam by the record may. as appropriate, be considered as directed to the portion of the beam affected by the record.

. Mv invention is notlimited to the particular apparatus and arrangement thereof, and circuits vvhich are illustrated, but may be modied without departing from the spirit and scope of my invention as set forth in the appended claims.

' What is claimed is:

1. The method of recording and reproducing signals employing a medium of opticallv active. light transmitting material which consists in moving the medium at 4substantially uniformv speed while modifying its light rotative characteristic in response to received signals, subsequently passing the medium through' polarized light which the medium rotatively modulates in accordance with the record on it and translating theresulting modulated light into signals corresponding to those received.

2. A signal recorder and reproducer including an extensive medium of light transmitting optically active material, means to change the light rotative characteristic of the medium in response to received signals to make a record of the signals along the medium, means to produce a beam of Apolarized light, means to pass theV medium through the beam to rotatively modulate it in accordance with the record and means responsive to the rotative modulation of the beam as the medium is passed `through it to produce signals in accordance with the record on the medium.

3. A sound recorder and reproducer including, in combination, a illament of optically active material, means to modify the light rotative characteristic of the lament in response to received sound waves to form a record of said waves, means to produce a beam oi.' polarized light, a polarizing medium intersecting the beam, means to drive the filament through the beam between `the medium for detecting the modulations of therbeam and converting them into sound waves.

4. A signal recorder and reproducer including, iii combination, a `:larnent of optically active material, means to modify the light rotative char acteristic of the lament in response to received signalsv to form a record of said signals, means to produce a beam of substantially monochromatic polarized light, a polarizing medium intertively modulate the beam and means including secting the beam,y means Yto drive the larnent through the beam between the producing means and the medium to rotatively modulate the beam and means including the medium for detecting the modulations of the beam and converting them into signals. f, 5. A sound recorderV and reproducer. including, in combination, a lament of optically active material, a rst spool to hold the lament, means to drive the filament, means to modify in response to sound waves the light rotative char-A acteristic of the lament as it is being driven, a take-up spool, means to drive the takeup spool, means'to maintain [the lament under tension as it is being driven, means to rewind the filament from the takeup spool to the` rst spool, means to produce a beam of polarized light through which the fila-ment bearing a record may be driven to modulate the beam in-at least one detectable characteristic including the vangle of polarization and means to convert thefmodulated beam into sound. y .Y

6. A sound recorder and reproducer including, in combination, a filament of optically active ma- A terial, a first spool to hold the filament, means to drive the lament, means to modulate the filament, includingv its light vrotative characteristie, in response 'to sound waves as it is being driven, a takeup spool, means to drive the takeup spool, means to maintain the iilament under tension asv it is being driven, means to'rewind the filament bearing a record from the' takeup spool to the first spool, means to produce a beam of substantially monochromatic polarized light through which the filament bearing a record may be driven to modulate the beam in at least one detectable characteristic including the angle cf polarization and means toicon'vert the modulated beam into sound. l 7. The method of reproducing signals from a medium of light transmitting optically activ material bearing a signal record of light rotative modulations which consists in passing the Yrecord through a beam of polarized light to rotatively modulate the beam in accordance with the record, converting the rotatively modulated beam into an intensitymodulated beam and convert'- ing the intensity modulated beam into signals.

8. Ay signal reproducing device including a long medium of optically active light transmitting material the light rotative characteristic of which hasbeen modied to form a signal record, means to produce a beam of substantially monochromatic polarized light, means to Ypass the medium through the beam to rotate the beam in accordance withthe record and means to convert the light beam thus rotated into signals;

9. A device toproduce signals from a substantially round flexible lament bearing undulations on not morethan two quadrants to form a sig'- nal record including, in combination, meanslto drive the lament longitudinally and detecting means cooperating with the filament as it is being driven to produce Vsigrialsin response' to Y the undulations thereon'for any 4rangle about its aids the' niemeer 'maybe presentes' to' the de: tecting means; Y

10. -A device to reproduce sound from a rec ord of optically active light transmitting material the light rotative characteristic of which has been modulated in accordance with'soun'd waves including means to producea beaml ci polarized light, means to drive the record through the beam to rotatively modulate it in accordance with the record and means responsive to the modulated beam to produce sound waves corresponding to the record.

11. A device to produce signals from a medium of optically active light transmitting material, the light rotative characteristic of which has been modulated to form a signal recordVi-nclud ing. in combination, means to produce a. `beam of polarized light, means to drive the medium through the beam to rotatively modulate the beamin accordance with the record, an analyzer including a photo-responsive element to receive themodulated beam and means including the photo-responsive element to produce signals corresponding to the record in response to the modulated beam. Y A

12. A device to produce signals fromarmedium vof optically active light transmitting material the light rotative characteristic of which hasbeen modied to form a signal record including, in combination, means to produce a beam of `particularly polarized light, a rpolarizing-eleq ment intersecting the beam and so oriented with respect to it as to normally substantially extinguish the beam, means to drive the medium through the beam above said element at'such angle with respectl to the polarization thereof that the portion of the beam corresponding substantially to the section of the medium therein will be rotated in accordance with the record to cause it to be transmitted beyond said element and means beyond said element to convert the beam into signals corresponding to the record.

13. A device to produce signals from a medium of optically active light transmitting material the light rotative characteristic of which has been modiiied to form a signal record including, in combination, means to produce a beam of substantially monochromatic polarized light, light polarizing means intersecting the lbeam and so oriented with respect to it as to normally substantially extinguish the beam, means to drive the medium through the beam above the polarizing means at such angle with respect to the polarization thereof that the portion of the beam ,o corresponding substantially to the section of the medium therein will be rotated in accordance with the record to cause it to be transmitted beyond the polarizing means and means beyond said polarizing means to convert the beam into signals corresponding to the record.

14. A reproducer of sound from a iilament of optically active light transmitting material bearing light rotative modulations to form a sound record including, in combination, means to produce a beam of polarized light, means including a motor to drive the record through the beam to cause the beam to be rotatively modulated in accordance with the record means to convert the rotatively modulated beam into an intensity moding" optically "soave pr0perty,-a 'supply' spool yor' said filament, a. takeup'spool for said filament;

mean's'to driveV the lament from the supply spool to the takeup spool, means to modify the iight rotative-v4 characteristic of the lament'vin response to received signals to make a record oi the signals on the filament as the latter is being driven from the supply spool to the takeup spool, means tovv rewind the filament from the takeupv spool 'to the supply spool, means including a; beam of polarized light passed throughthe viilament bearing a record for reproducing signals from the filament corresponding to those record" edffas the filament is driven from the supply spool to the takeup spool and means to control se@ lectiveiy the operations of recording, rewindin'g and reproducing. c 16. A signal recorder and reproducer includ ing, in combination, a filament of optically active material, means to drive the iilament, a signal input circuit, an amplier, a recorder element responsive to received signals to modify the light rotative characteristic of the filament as it is being drivento record said signals on said filamerit, means to produce a beam oi polarized light through which the iilament bearing a record is driven to rotatively modulate the beam in accordance with the record on the filament, reproducing means to convert said rotatively modulated beam into signals corresponding to those recorded, a signalv output `circuit 'and1 meansto connect the amplifier between the signalv input circuit and the recorder element'during the recording" operation, and between the reproducing means andthe signal output circuit 'duringrthe reproducing operation. f 17. 'A signal recorder and reproducer including afilament of optically active material, a supply spool, a takeup spool, means selectively operable to drive the lament from the supply spool to the takeup spool or to rewind the filament from the takeup spool to the supply spool, a blade member adapted to engage the filament and place thereon light rotative modulations in response to received signals as the iilament is being driven from the supply spool to the takeup spool, means including a beam of polarized light through which the iilament bearing a record is driven from the supply spool to the takeup spool for reproducing signals from the record on the filament and means for maintaining the blade l member out of engagement with the iilament except when a record is being made.

18. A device to produce signals from a iilament of light transmitting material having an oriented grained structure and bearing a signal record consisting of undulations including, in combination, means to drive the filament, means to scan the filament with polarized light with at least a portion oi the rays of said light including an angle of substantially said lament being effective to modulate said light in accordance with the recorded signals, and means to convert the modulated light into signals.

19. A reproducer of signals from a normally substantially round extensive iiexible medium of light transmitting material having an oriented grained structure and capable of refracting light and which |bears an undulatory signal record including means to produce a thin beam of polarized light, means to pass the medium in a predetermined direction through the beam at substantially uniform speed, the medium being presented to the beam at chanoed orientations around the longitudinal axis of the medium, the

record being eil'ective to impart to rays .ofA thev bea-m refractive modulations and rotative ,modu` lations, and means to convert the two-typeswof modulated rays into signals, the effect on last said means of each type of modulation at any instant bearing a substantially inverse relation to each other dependent on the angular-orientation of thelament to the beamV whereby` the amplitudey of said signals is substantially independent of the angular orientation of the medium to the beam. i

. 20. A signal recorder including a exible light transmitting medium, means to drive the medium and means selectively operable to place modulations on said medium in response to signals from a certain source to .make a record'of said signals as the medium is being driven or to place modulations on said medium other than in response to' signals from said source, either of said modulations ibeing of such characteras to be detectible by a scanning beam ofpolarized light.

21. A signal recorder including a medium of birefringent material, means to drivei the medium, means to modify the birefringency of the medium in response to signals asthe medium is being driven and a second means to modify the birefringency of the medium as it is being Mdriven. v

22. A device to produce signals from a substan-Y tially round lament of light transmitting material of homogeneous cross section bearing a signal record on not more than two quadrants which is capable of modulating rays of light passed through the record as the lament is being driven including, means to drive the lament in random orientations of it around its longitudinal axis, means to pass through said lament, as it is being driven, thin converging scanning light which REFERENCES CITED The following references are or record inthe ille of this patent:

UNITED STATES PATENTS Number l Name y Date 789,336 Poulsen May 9, 1905 1,335,595 Moore Mar. 30, 1920 1,350,246 Steiger Aug. 17, 1920 1,681,376 Snook Aug. 21, 1928 1,802,747 Zworykin Apr. 28, 1931 1,917,003 William v July 4, 1933 1,918,848 Land July 18, 1933 1,946,596' Symonds Feb. 13, 1934 2,086,130 Hickman July 6, 1937 2,188,687 Lohn Jan. 30, 1940 2,213,250 Kotte Sept. 3, 1940 2,215,468 VHerzig Sept. 24, 1940 2,220,488 i Lott Nov. 5,1940 2,256,093 Land Sept. 16, 1941: 2,263,316 Ryan Nov.l 18, 1941 FOREIGN PATENTS Number Country Date 4633,624 France Oct. 25, 1927 276,708 Great Britain sept. 1, 1927 384,258 Great Britain Dec. 22, 1932 

